1. Field of the Invention
The present invention relates to a hand-held power tool connectable, if necessary, with a dust suction module for aspirating the to-be-removed material produced during the operation of the power tool.
2. Description of the Prior Art
The hand-held power tool, which is connectable with the dust suction module, includes a motor and an air flow generator that for cooling the motor is located, together with the motor, in a cooling flow path between an air inlet and an air outlet which are formed in the tool housing. The dust suction module is provided with a suction conduit that adjoins the inlet so that a connection between the suction path of the dust suction module and the cooling flow path can be established.
Hand-held power tools of the type discussed above can be rapidly and simply equipped with a dust suction module, when needed, in order to remove material which is produced during operation of the tool, such as drillings, dust, or saw chips. The dust suction module can be made particularly light and compact as it does not require an air flow generator. Rather, the air flow generator produces both air flow which is required for cooling the motor, and air flow which is required in the suction path and with which the removable material is aspirated.
U.S. Pat. No. 5,113,951 discloses a drilling tool the drive gear housing of which has an air inlet. With a ventilator mounted on the motor shaft, air is aspirated through the air inlet and is circulated along a cooling flow path in the interior of the tool housing past the motor for cooling the same. Finally, a heated air, which is produced as a result of cooling the motor, exits through an air outlet which is formed, with respect to the operational direction of the drilling tool, behind the inlet. The air inlet is so formed that a free end of the suction conduit of the dust suction module can be inserted thereinto. In this way, the air necessary for cooling the motor is aspirated through the dust suction module that also serves for aspiration of drillings. The air is used for cooling the motor after it passes a filter.
The drawback of the drilling tool which is disclosed in U.S. Pat. No. 5,113,951, consists in that with the dust suction module having been removed, there exists a danger that a non-purified air would be aspirated for cooling the motor. This can lead to damage of both the motor and the drive gear. This danger is enhanced by the position of the air inlet in the housing close to the working tool, so that dirt can enter into the cooling air path with a particular ease. The position of the air inlet in the vicinity of the working tool is, however, necessary in order to be able to achieve a high suction capacity. Further, there exists a danger that during the operation with the dust suction module, its filter will be so clogged that a sufficiently high air flow for cooling the motor would not be available. This can result in damage of the motor and in reduction of the service life of the motor and the power tool.
Accordingly, an object of the present invention is to provide a hand-held power tool in which the drawbacks of a prior art power tool are eliminated.
Another object of the present invention is to provide a hand-held power tool in which a reliable cooling of the motor is insured.
A further object of the present invention is to provide a hand-held power tool in which a high suction capacity is insured even when a dust suction module is used.